Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, monolithic windows, and/or the like.
Conventional low-E coatings are disclosed, for example and without limitation, in U.S. Pat. Nos. 6,576,349, 9,212,417, 9,297,197, 7,390,572, 7,153,579, and 9,403,345, the disclosures of which are hereby incorporated herein by reference.
Certain low-E coating utilize at least one transparent dielectric layer of titanium oxide (e.g., TiO2), which has a high refractive index (n), for antireflection and/or coloration purposes. See for example U.S. Pat. Nos. 9,212,417, 9,297,197, 7,390,572, 7,153,579, and 9,403,345. Although high refractive index dielectric materials such as TiO2 are known and used in low-E coatings, these materials are not thermally stable and are typically not heat stable after tempering process of about 650 C for 8 minutes, due to film crystallization (or change in crystallinity) in as-deposited or post-tempering state, which may in turn induce thermal or lattice stress on adjacent layers in the film stack. Such stress can further cause change in physical or material properties of the stack and hence impact on the Ag layer, which results in deteriorated low E stack performance. In other words, conventional TiO2 layers are typically sputter-deposited so as to realize a crystalline structure, which leads to damage to the stack upon HT as explained above.
Example embodiments of this invention solve these problems by providing a high index doped titanium oxide layer for use in low-E coatings that both has a high refractive index (n) and is substantially stable upon heat treatment (HT).
“Heat treatment” (HT) and like terms such as “heat treating” and “heat treated”, such as thermal tempering, heat strengthening, and/or heat bending, as used herein means heat treating the glass substrate and coating thereon at temperature of at least 580 degrees C. for at least 5 minutes. An example heat treatment is heat treating at temperature of about 600-650 degrees C. for at least 8 minutes.
In example embodiments of this invention, a coated article includes a low emissivity (low-E) coating having at least one infrared (IR) reflecting layer of a material such as silver, gold, or the like, and at least one high refractive index dielectric layer of or including doped titanium oxide (e.g., TiO2 doped with at least one additional element such as Nb, Sn, ZnSn, Y, Zr, and/or Ba). The doped titanium oxide layer(s) is designed and deposited in a manner so as to be amorphous or substantially amorphous (as opposed to crystalline) in the low-E coating, so as to better withstand optional heat treatment (HT) such as thermal tempering. For example, it has surprisingly and unexpectedly been found that sputter-depositing the doped titanium oxide layer(s) in an oxygen depleted atmosphere results in the doped titanium oxide layer being deposited in an amorphous or substantially amorphous (as opposed to crystalline) state as well as having desired transmission characteristics, which in turn allows the layer and overall coating to be much more stable upon HT. The high index layer(s) may be a transparent dielectric high index layer in preferred embodiments, which may be provided for antireflection purposes, transmission, and/or color adjustment purposes, in addition to having thermal stability. In certain example embodiments, the low-E coating may be used in applications such as monolithic or insulating glass (IG) window units, vehicle windows, or the like.
In an example embodiment of this invention, there is provided a coated article including a coating supported by a glass substrate, the coating comprising: a first transparent dielectric layer on the glass substrate; an infrared (IR) reflecting layer comprising silver on the glass substrate, located over at least the first transparent dielectric layer; a second transparent dielectric layer on the glass substrate, located over at least the IR reflecting layer; and wherein at least one of the first and second transparent dielectric layers is amorphous or substantially amorphous, and comprises an oxide of Ti doped with at least one of Nb, Sn, SnZn, Zr, Y, and Ba, and wherein metal content of the amorphous or substantially amorphous layer comprises from about 70-99.5% Ti and from about 0.5-30% of at least one of Nb, Sn, SnZn, Zr, Y, and Ba (atomic %).
In another example embodiment of this invention, there is provided a coated article including a coating supported by a glass substrate, the coating comprising: a first transparent dielectric layer on the glass substrate; an infrared (IR) reflecting layer comprising silver on the glass substrate, located over at least the first transparent dielectric layer; a second transparent dielectric layer on the glass substrate, located over at least the IR reflecting layer; and wherein at least one of the first and second transparent dielectric layers is amorphous or substantially amorphous, and comprises an oxide of Ti and Nb, and wherein metal content of the amorphous or substantially amorphous layer comprises either: (a) from about 30-70% Ti and from about 30-70% Nb (atomic %), or (b) from about 70-99.5% Ti and from about 0.5-30% of at least one of Nb, more preferably from about 80-99% Ti and from about 1-20% of at least one of Nb, and sometimes from about 87-99% Ti and from about 1-13% Nb (atomic %).
In another example embodiment of this invention, there is provided a method of making a coated article including a coating supported by a glass substrate, the method comprising: sputter depositing a first transparent dielectric layer on the glass substrate; sputter-depositing an infrared (IR) reflecting layer comprising silver on the glass substrate, located over at least the first transparent dielectric layer; sputter-depositing a second transparent dielectric layer on the glass substrate, located over at least the IR reflecting layer; and wherein at least one of the first and second transparent dielectric layers is sputter-deposited so as to be amorphous or substantially amorphous, and comprise an oxide of Ti and at least one of Nb, Sn, SnZn, Zr, Y, and Ba. The at least one of the first and second transparent dielectric layers sputter-deposited, so as to be amorphous or substantially amorphous, may be sputter-deposited in an oxygen depleted atmosphere so that a difference in radii for metals during sputtering causes lattice disorder leading to amorphous or substantially amorphous structure of the layer.